Laser interstitial thermal therapy (LITT) is a clinical tool for treating various malignant tumors in the liver, brain, ENT, or abdominal locations, as well as for treating benign alterations, such as prostate adenomas. Fiber optics that terminate in either bare fibers or diffusing applicators are punctured into the pathological volume to deliver the laser energy within the desired region of treatment. After positioning of the fibers, target tissues are irradiated causing volumetric heating that leads to thermal tissue necrosis. Tumor destruction with direct heating is therefore possible, while greatly limiting side effects or additional damage to surrounding structures. Furthermore, such thermal methods are associated with faster recovery than conventional surgical resection procedures.
Large applicators may cause trauma to healthy tissue when accessing the pathological volume. Applicators where light distribution results in high power density and heat generation, exceeding the thermal diffusion into the tissue can cause areas close to the applicator to char and potentially vaporize. Charring limits heat deposition within deeper tissue volumes due to increased absorption of light energy. As charred tissue continues to absorb incident light, its temperature continues to rise, leading to carbonization around the applicator. Further coagulation of deeper layers is dependent on heat conduction away from this carbonized volume.
While it is indeed possible to create large thermal lesions in this manner, the morphology of the resulting lesion is undesirable. Furthermore, high temperatures associated with the carbonized tissue often result in failure of the applicator tip and fiber optic with significant attendant risk for patients. As such, an applicator that limits charring and vaporization would be desirable.
Typical applicators are multi-component applicators. Procedures utilizing these applicators involve multiple insertion steps and time consuming actions taken by the medical professional performing the procedure. Such steps and actions prolong the surgical process and endanger the patient. In addition, multiple insertion steps potentially cause slippage of catheters and additional damage to surrounding tissue. As such, an improved applicator would be desirable.